Spiral stairway



A. L. SMITH.

SPIRAL STAIRWAY.

APPLICATION FILED MAY 27, 1919.

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3. W uw'mg ms (5%Za r174? ARTHUR I1. SIJIITH, 0F IFIELROSE, MASSACHUSETTS.

SPIRAL STAIRVJAY.

Specification of Letters Patent.

Patented Dec. 14, 1920.

Application filed. May 2'7, .919. Serial No. 300,079.

T 0 all whom it may concern Be it known that I, ARTHUR L. SMITH, a citizen of the United States, and resident of Melrose, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Spiral Stairways, of which the following is a specification.

This invention relates to a spiral stairway and particularly to a stairway having sepa rate stair elements, which may be assembled to constitute a stairway of any desired length. An object of the invention is to provide stairway elements comprising simple and substantial parts which may be easily assembled to constitute a stairway or" desired length with either a right or left hand spiral. A further object of the invention is to provide a stairway element constructed largely of standard structural iron shapes. Further objects ofthe invention will appear as the description progresses.

Figure 1' is an elevation, partly diagrammatic, of a spiral stairway constructed according to my invention;

Fig. 2 is a lateral section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 1 and shows in plan view, an assembly of two stair elements;

Fig. 4 is an elevational view of the stair elements shown in Fig. 3;

Fig. 5 is a plan view of a modified form of stair element;

Fig. 6 is an elevational view of the stair element shown in Fig. 5; and

Fig. 7 is an enlarged sectional view taken on the line -7 of Fig. 4.

In Fig. 1, I have shown partly diagrammatically, a spiral stairway built up from separate elements 1, assembled one above the other and united by the handrail 2. Each element 1, according to the embodiment illustrated in Figs. 1, 3, 4 and 7 comprises a cast hub 3, provided at its upper end with a bell 4, within which the hub 3 of the stair element next above rests. By providing each hub member 3 with a belled end an important advantage in assembling the several parts of the stairway is obtained, since thereby means is provided not only for receiving and supporting hub members 3 superimposed upon each other, but also means is provided for holding in alinement the hub members 3 and their coiiperating treads 13, so that the openings in the treads may be readily and accurately alined to receive the palings 15 in assembling. Cast integrally to the side of the hub and just below the bell 4 is a square shoulder 5,

bolt 8 or any other suitable means .is a hori-' zontal tread support 9, and secured to the lug 7 by bolt 10 and to the support 9 by bolt 11 is a brace 12. The support 9 and brace 12 are preferably formed from angle iron, although any other suitable structural shape could be used. To the upper face of the support 9 and abutting the shoulder 5 of hub 3 a tread 13 is secured by bolts or rivets 14. This tread 13 may be formed from steel plate and its upper or wearing surface checkered for the purpose of affording a more secure foothold or the tread may be cast in the desired shape.

As shown in Fig. 3, each stair tread 13 is triangular in outline and provided at its outside corners with openings through which the palings 15 pass. Each paling 15 is provided at its lower end with a square head 16 which engages beneath a tread 13 and passes through the rear one of the openings therein and through sleeve 17 which separates tread 13 from the tread 13 next above it. Paling 15 then passes through the forward opening in tread 13 next above and screws into a threaded opening in the underside of rail 2.

It is thus obvious that when the stair elements 1 are assembled one above the other with the hub 3 of one element resting in the bell 4 of the element next below it and the palings 15 are inserted through the rear outer corner of the tread 13 of one element and the front corner of the tread of the element next above it and secured in the spiral railing 2, that the elements 1 form a stairway which spirals around the column of hubs 3.

In Figs. 5 and 6, I have illustrated a modified form of my invention which is substantially similar to the form shown in Figs. 3 and 4 except that support 9 and tread 13 have been combined into a unified element 18 which serves both a support and a tread. The element 18 comprises a flat surface or tread portion 19 and an overturned edge or flange 20 which bolts to lug 6 on hub 3 by means 01 bolt 8. The brace 12 is secured to the flange 20 and lug 7 on hub 3 by bolts 11 and 10 as in the embodiment above described. The outer ends of theelements 18 are secured in position relative to each other by pailings 15 as explained in connection with Figs. 3 and 4.

In Flg. 5, I have showirthe tread'rounded at 21, rather than out straight as in Fig. 3..

also be: provided. with suitable; bolt holes (not shown); through which bolts or lag screws may be: inserted for securing it to the-fioon Fromtheforegoing: description it will appear that-I have provided a spiral stairwaywhich: may be easily assembled from 7 separate" stair elements tobuild up az stair way of! any desired length; That each; stair element-is oomposedof few andis-imple'parts which: may" be shipped in: a complete knocked down condition and quickly assembled on the: j .ob thus eliminating an assembly at thefactory andl the" shipping of a bulky and unW-ieldly structure. A; further advantage. lies in the fact;v that: by/ utilizing angle= iroir supports and braces for the t'reads the: central= hub may bee form'edl as a simpler casting than would result if the entire stair element were cast integrally.

I claim: 7 1. In aspiral stairway, a stair element comprising a central supporting member, lugs formed integrally with said member, a tread having an overturned flange secured to one ofsaid lugs and a brace'connecting saidlfiange withthe other of said lugs.

' vertically spaced lugs projecting; from: said member, tread, having an integra'll sup:- pontingymemben secured tov theeuppea' of: said lugs; and. a: brace secured to thelower of said lugs andto the-supportingmember;

4;. In a spiral stairway; a stair element comprising a central supporting member, vertically spaced lugsprojecting from said m'ember and! arsquared shoulden'iiormed ad j a'cent; the l uppeir lug a lfiBitCli abutting against said shoulden'and having an integral supporting member secured to the upper of: said lugs; and brace secured to the lower of said: lugs and to the suppiortingmember acl;'a'centf its outer end; V

kigne'd. by. me ati Boston, Massachusetts this fourteenth day ofvMay;1919;: 7

' ARTHUR L. SMITH} 

